She said: “A possible reason for why he should be in Willesden or Harlesden emerged from a mutual friend of theirs who also goes to Capital City Academy.

“This friend had some disagreements with [the suspect] over the weekend on social media and almost dared him to come up to Harlesden but thought that he wouldn’t because he knew that [the suspect] was living in the Norwood area at the time.

“There is no doubt that he did leave the area. He did so to go and wait outside the school. He waited for Quamari and as soon as he saw him, he chased and stabbed him.”